Unless you're playing River Song, that is, a new MTG Doctor Who Commander card with an innovative effect that's caused quite a bit of buzz in the Magic community
Enchantments like Smile at Death (from Tarkir: Dragonstorm ) give your ETB creatures a second wind, while staples like Doubling Season double your output
This goes best in decks with huge creatures like that its up to you whether thats because of their base power, or because of lords, +1/+1 counters, equipment, or any number of other ways to make huge creatures to attack with
At the beginning of combat on your turn, if you control two or more other legendary creatures, you may transform Serah Farron
I dont truly have any statistics to justify saying this is better than having them draw on each of their own turns, but it gives me a greater sense of security